Means for controlling guide bars in warp knitting machines

ABSTRACT

A mechanism controlling longitudinal movements of guide bars in a warp knitting machine. It separates selections of such movements to the extents of different needle spacings from the driving influence effecting the same. The mechanism comprises, for each guide bar, (a) a driving unit incorporating not only slides profiled to provide a cam face and operable to vary the latter but also a continuously driveable radius lever with a follower for following the cam face and transmitting required movements to the guide bar; and (b) a separate program unit outputs from which effect movements of the slides to vary the profile of the cam face. (a) functions to move the guide bar only after (b) has determined the extent and direction of such movement.

United States Patent [72} Inventor Roy Farwell Derbyshire, England 1211 Appl. No. 35,820 [22] Filed May 8, I970 [45] Patented Dec. 21,1971 [731 Assignee Clutsom-Penn International Limited Highlields, Coalville, Leicestershire, England [32] Priority May 27, I969 [33] Great Britain [31] 26,611/69 154] MEANS FOR CONTROLLING GUIDE BARS IN WARP KNITTING MACHINES 16 Claims, 9 Drawing Figs.

[52] U.S.Cl 66/86, 66/154 [51 1 Int. Cl D046 23/00 [50] Field of Search 66/116,84, 154

[56] References Cited UNITED STATES PATENTS 2,106,434 1/1938 Morton etal. 66/86 Primary Examiner-Ronald Feldbaum AttorneyLarson, Taylor & Hind's ABSTRACT: A mechanism controlling longitudinal movements of guide bars in a warp knitting machine. It separates selections of such movements to the extents of different needle spacings from the driving influence effecting the same. The mechanism comprises, for each guide bar, (a) a driving unit incorporating not only slides profiled to provide a cam face and operable to vary the latter but also a continuously driveable radius lever with a follower for following the cam face and transmitting required movements to the guide bar; and (b) a separate program unit outputs from which effect movements of the slides to vary the profile of the cam face (a) functions to move the guide bar only after (b) has determined the extent and direction of such movement.

PATENTEU 05021 1911 SHEET 1 OF 5 WENIED 05221 137:

SHEET .13 [1F 5 MEANS lFOR CONTROLLING GUIDE BARS llN WARP KNl'lf'llllNG MACHINES This invention relates to warp knitting machines of the class equipped with one or more guide bars, and has reference particularly to means for controlling the longitudinal movements of such bars.

Broadly considered, a warp knitting machine or loom" as it is often called includes, in combination, a needle bar which carries leads into which needles are cast, at least one guide bar furnished with a set of guides which are cooperable with the needles, the guides having eyes through which are passed individual warp threads of a sheet of warps drawn from a beam,

and operating and controlling means adapted to impart motions to the needle bar and to the guide bar or relevant guide bars respectively whereby warp threads become looped, i.e.

lapped, around the needles, and the latter produce from these threads a basic knitted structure comprising laterally connected wales of knitted loops. Thus, in such a warp knitted fabric, adjoining vertical wales of knitted loops are laterally connected either in successive or in spaced courses or laps" as they are called.

Warp knitting machines are, however, often furnished with guide bars which do not cooperate with the needles in the production of the basic structure of a warp knitted fabric, but function merely to layin fancy or patterning yarns or threads into a basic structure without the said laid-in-yarns or threads being knitted.

A guide bar which is cooperable with needles in the production of a basic fabric structure as aforesaid is conventionally adapted to be swung backwards and forwards between the needles in addition to being individually movable longitudinally (i.e., shogged laterally with respect to the fabric) in both directions for underlaps and overlaps of varying extents in accordance with pattern requirements. It has, however, been proposed to provide guide bars which, although they cooperate with needles in the knitting of a basic swung structure, nevertheless are not swing backwards and forwards between needles but are simply movable longitudinally in which instance to enable the lapped threads to be taken and engaged by the needles, the needle bar itself has imparted thereto special movements relatively to the guide bars. But whether a guide bar which cooperates with needles for knitting, is swung backwards and forwards or not it has imparted to it two longitudinal movements per machine cycle.

On the other hand, a guide bar used solely for laying-in, only has imparted to it one longitudinal movement per machine cycle.

The invention is more especially applicable to any appropriate warp knitting machine equipped with a minimum of two guide bars capable of being selectively controlled in regard to their longitudinal movements, i.e., their shogging movements laterally with respect to the fabric width. It is, however, principally the intention to apply the invention to multibar warp knitting machines having say, four or more guide bars.

Moreover, the invention is equally applicable to bearded needle machines, Raschel machines equipped with latch needles, so-called F.N.F. machines and Simplex warp knitting machines having two sets of needles.

in a conventional warp knitting machine of the class concerned, the longitudinal movements of the guide bar or bars are usually controlled by cam discs or chains of cam lines arranged to operate directly upon the relevant end or ends of the said bar or bars. Such cams or cam links require to be very accurately ground to move the guide bars precisely over the required numbers of needles spaces, and may even need to be ground specially for a particular fabric design, in order to obtain smooth longitudinal motions. For each guide bar one or two separate cams or cam links is or are required per course in the pattern repeat. ln such a prior arrangement, the selection of a required movement of a guide bar, predetermined by a program as to its extent and direction, and the actual longitudinal movement imparted to the said bar as a consequence of such selection take place simultaneously.

An object of the presentinvention is to provide, in or for a warp knitting machine of the class herein referred to generally improved means for controlling the longitudinal shagging movements of one or more guide bars, said means being designed to separate selections of such movements from the driving influence actually effecting the movements.

Another important aim of the invention is to make possible the use of a selection or program unit which does not require to be as accurate as the conventional cams or cam links heretofore employed.

The control means according to this invention comprise, in combination for the or each guide bar to be controlled, (a) a driving unit incorporating both means providing a cam face and operable to vary the profile thereof and also continuously driveable means for following such face and thereby conveying varying longitudinal movements to the guide bar by cam action, and (b) a separate selection or program unit outputs from which effect variations in the profile of the cam face, (a) functioning to move the bar longitudinally after (b) has determined the extent and direction of the movement.

Since the selection and the longitudinal movement of a guide bar are no longer simultaneous, the following important advantage is derived, viz a longer time for selection is made available, this in turn:

1. enabling a more flexible selection system to be adopted,

and

2. providing the possibility of employing any desired one of a wide range of selection or program units or systems, as will be hereinafter described.

For each guide bar (a) conveniently comprises relatively movable components individually profiled to provide portions of the variable cam face, a first member which is connected a one end with the said guide bar and is arranged at the other end to follow the cam face, and a second member which is connected to or with the first member and is adapted to be continuously driven from a suitable drive source suchwise as to move the relevant end of the first member to and fro relatively to the cam face. As to (b) in such an arrangement, this effects selective movements of the profiled components relatively to one another for the purpose of modifying the cam face and thereby subsequently changing the position of the guide bar by a longitudinal movement thereof the extent and direction of which have previously been determined by (b).

According to an important feature of the invention, latching devices of any appropriate character are provided to accurately locate and lock the aforementioned individually profiled components in the positions to which they are selectively moved by the unit (b).

In a convenient embodiment of the invention there is, to each guide bar a pair of individually profiled components, in the form of slides, and one latching device per slide. For example, each such latching device comprises opposed series of pointed teeth, the teeth of one series being formed on the relevant profiled slide and the teeth of the opposed series being formed on an adjacent and relatively movable element. Whenever the device is closed to lock the relevant slide the teeth on the latter are engaged in the complementary V-shaped notches between the teeth on the opposed latch element. Each latching device is opened, to unlock the corresponding slide by movement of the latch element away from the said slide in a direction transverse to longitudinal movements thereof. When, on the other hand, the teeth on the latch element are moved into engagement with the teeth on the profiled slide to close the latching device and so lock the slide, the opposing teeth, as a consequence of being fully interengaged, may cause a slight movement of the slide to locate it accurately in its required position. In this regard it is necessary to explain that the effective gauge or pitch of the pointed teeth of each latching device is the same as the gauge or pitch of the needles of the warp knitting machine; consequently, the formation and operation of the latching devices ensure accurate location of the guides with respect to the needles.

Of the two opposed series of teeth of each latching device one moves longitudinally together with the relevant profiled slide while the other, borne by the latch element, is movable in a direction perpendicular with respect to the line of longitudinal movement of the. said slide. Each latch element is mounted on a block or the like movable in a fixed part of (a). The movable blocks or the like may be spring biased normally to hold the latch elements apart from the profiled slides, any suitable means operable either form the machine drive or from the aforesaid second member which is connected to or with the first member, e.g. through the medium of tappets, plungers and rockers, being provided to move the latch elements into engagement with the profiled slides against the spring action.

Advantageously, the aforesaid first member in each unit (a) may consist of a radius lever which at its relevant end is pivotally connected to a slidable crosshead in turn connected with the relevant guide bar, and at its opposite end is furnished with a follower arranged to run on and over the cam face: in this case, at least part of the profiled end of each of the relatively movable components provides a cam face portion in the shape of an arc whose radius in the effective length of the radius lever.

It is preferred that the unit (b) shall be of an electropneumatic character, the programming being carried out by a peg board, and the necessary movements of the relatively movable profiled components being effected through the medium of pneumatic cylinders and associated output shafts or spindles arranged to act selectively upon the profiled components. Such a system is very versatile and patterns can be changed even while the machine is knitting. A similar but more compact, and yet equally versatile, separate selection or program unit may be controlled from punched tape.

Alternatively selection or program units which may be used are ones of an electromechanical, electrohydraulic, electronic-pneumatic, electronic-hydraulic, hydraulic or pneumatic character.

It is also possible for (b) to consist of a cheap and wholly mechanical cam chain in which the cam links are not as accurate as the conventional cam links heretofore used.

In order that the invention may be more clearly understood and readily carried into practical effect, the general application thereof to a warp knitting machine of the class concerned,

and specific constructional examples of the improved guide bar controlling means will now be described with reference to the accompanying drawings, wherein,

FIG. 1 is a fragmentary perspective view of so much of a warp knitting machine as is necessary to illustrate the driving unit and the associated selection or program unit for selectively acting upon guide bars,

FIG. 2 is a side elevation of a form of driving unit suitable for producing one longitudinal movement of a guide bar per machine cycle, i.e., for laying-in yarn, a portion of the separate selection or program unit being shown at the righthand side of the figure,

FIG. 2A is an inset diagram of one of the latching devices,

FIG. 3 is a view similar to FIG. 2 illustrating the parts in other positions,

FIG. 3A is an insert diagram of one of the latching devices in a locked position,

FIG. 4 is a timing diagram relating to the example illustrated in FIGS. 2, 2A and 3,

FIG. is a side elevation of another form of driving unit suitable for producing two longitudinal movements of a guide bar per machine cycle, for use when knitting, 7

FIG. 5A is a timing diagram relating to the example illustrated in FIG. 5, and

FIG. 6 is a part-sectional view of the separate electropneumatic selection or program unit adapted for use with either of the two driving units illustrated in FIGS. 1 and 2 and in FIG. 4 respectively.

Referring to FIG. 1, the letter 0 indicates the main frame of a warp knitting machine. At b is shown a portion of the needle bar of the machine equipped with needles 0. One guide bar,

co'operable with such needles, is indicated at :1, this bar being.

furnished with guides e. These guides have eyes through which are passed individual warp threads t of a sheet of warps drawn from a beam f. The needle bar b is movable up and down as indicated by the arrows g. The guide bar d is adapted to be swung backwards and forwards between the needles 0, in the direction of the arrows h, by a swing shaft motion such as that designated i. In addition, the illustrated guide bar d (one of many) is individually movable to varying extents longitudinally to the left in FIG. 1, by virtue of being acted upon selectively by a driven link 18, and longitudinally to the right by means of a tension spring .r when the driving force on the said link has been relaxed. Thus, the longitudinal shogging movements of the guide bar d are in the directions indicated by the arrows j. The link 18 is connected to a crosshead 17 forming part of a driving unit shown generally at DU in FIG. 1. The selection or program unit for determining the extents of the leftward movements of the link 18 is similarly generally shown at PU.

In the constructional arrangement shown in FIGS. 2 and 3, the main drive shaft 1 of the warp knitting machine is connected, through 2:1 gear box 2, to a double-ended crank shaft 3 which drives a member 4 through the medium of connecting rods such as 5. In fact, although there is one member 4 per guide bar d (FIG. 1), there are only two of the connecting rods 5 which latter are arranged at opposite sides of the machine and are connected at their upper ends by a cross-shaft 6 upon which the lower ends of all the members 4 are pivotally mounted. Each member 4 is articulated to, and is arranged to drive both upwardly and downwardly, a radius lever 7. The inner free end of this lever 7 is furnished with a follower roller 8 which runs over and follows a cam face made up of segments 9, 10 and 11. The segments 9 and 11 are on the shape of arcs the radius of each of which is the effective length of the radius lever 7. Also, 10 is a bridging link with a planar surface. The output from the separate selection or program unit PU is fed to two shafts 12 and 13 which act upon profiled slides 14 and 15 the inner profiled ends of which constitute the segments 9 and II aforesaid. As will be seen the slides 14 and 15 are biased by tension springs S. Thus, the shafts 12 and 13 push the said slides leftwards against the springinfluence and control rightward movements of the slides under the same influence. The outer end of each radius lever 7 is pivotally connected at 16 to the horizontally disposed slidable cross head 17 which is in turn connected to the link 18 arranged to bear upon the appropriate endof the corresponding guide bar d.

The profiled slides 14 and 15 are accurately located and locked by latching devices, such as 19 and 20, operated by rotary cams 21 and 22 respectively. As shown in FIG. 2A each such device comprises a row of pointed teeth 23 on the relevant profiled slide and an opposed row of identical teeth 24 formed on a latch element 25. The latch element is mounted within a block 26 movable in a direction at right angles to the profiled slide. Each block 26 is controlled by compression springs 27 biasing the corresponding latch element 25 in a direction away from the slide. The rotary earns 21 and 22, e.g., indirectly driven from the main drive of the machine, act on follower rollers 28 carried by levers 28 which have abutment screws 29 for action upon the blocks 26. Thus, the said cams move the blocks 26 against the action of the springs 27 to close the latching devices. The gauge of the teeth 23 and 2 4 is the same as the gauge of the knitting machine. In operation, while the follower 8 on the radius lever 7 is moving over the are 9, as shown in FIG. 2, the corresponding guide bar is not moving in either longitudinal direction but is swinging through the needles and back. As to this, the readers attention is directed to the timing diagram constituting FIG. 4 and which represents one complete machine cycle.

The outer arrowed semicircle k at the left-hand side of this diagram indicates the radius lever 7 descends through one revolution of the machine, whereas the outer arrowed semicircle 1 at the right-hand side similarly indicates that the said arm ascends during another revolution. In this regard each of the two double arrowed curved lines m in FIG. 4 represents one revolution of the warp knitting machine. The two similar lines n represent the periods of time when guide bars d are traversing, i.e., being shogged longitudinally, and each of the two double arrowed lines represent a dwell period when guides are passing between needles c.

During the period the latching device 20 is locked, the latching device 19 is opened, the program unit PU selects the movement required during the next revolution of the machine and the shaft 12, and hence also the profiled slide 15, accordingly move to the new positions shown in FIG. 3. The latching device 19 is thereupon locked and the segments 9, l0 and 11, then provide suitably profiled cam surface for the roller 8 to follow. As the radius lever 7 descends over the bridging link 10, the cross head 17 and the corresponding guide bar d are driven to their new position and remain stationary in a longitudinal direction while the follower 3 is traversing the segment 11 shown in FIG. 3. During this time the latching device 20 is opened, shaft 13 and the profiled slide 14 are moved to a required new position and the said latching device 20 is again locked. The operation, as the radius lever 7 swings upwards during the next revolution of the machine, follows a similar sequence. The time allowed for selection of any required movements is approximately 67 percent of the machine cycle, while the time taken in actually moving the guide bar d from one longitudinal position to another is only 33 percent of the machine cycle.

in the example illustrated in FIGS. and 5A, there is mounted on the main drive shaft 30 of the warp knitting machine a double-acting cam 31 adapted to drive a member 32 vertically upwards and downwards slidably in bearings 33. The timing of the movements of the member 32 is controlled by the peripheral contour of the cam 31. lPivotally mounted upon the slidable member 32, intermediate its ends, are two opposed two-armed levers 34 for each guide bar which levers are furnished with rollers 35 for constituting bearings for a radius lever 36. The lever 36 is accordingly driven up and down by the member 32. The outer end of each radius lever 36 is pivotally connected at 37 to a crosshead slide 38 which acts on a link 39 in turn adapted to bear upon the end of a guide bar d. The inner free end of each radius lever 36 is furnished with a follower roller 40 arranged to run over surfaces 41 and 42 or 43 and 44 on a profiled slides 45 and 46 respectively, thereby imparting movements to the link 39 and hence also to the corresponding guide bar. The surfaces 41 and 44 are each in the form of an arc of radius equal to the effective length of the radius arm 36. Surfaces 42 and 43 are planar. The pairs of surfaces 41 and 42 and 43 and 44 are, of course, the profiled ends of the slides 45 and 46 the positions of which latter are selectively determined by the output from the selection or program unit PU. The said profiled slides 45 and 46 are accurately located and locked in position by the latching devices 47 and 48 respectively, such devices being of the same general character as the latching devices 19 and already described herein.

The latching devices 47 and 48 are operated from the corresponding vertically slidable member 32, through the medium of tappets 49 and 50, plungers 51 and 52 and rockers 53 and 54.

Let it be assumed that the upstroke of member 32 produces the underlap, i.e., the yarns are traversed in front of the needles. At the commencement of this upstroke, the latching device 48 will be open and the latching device 47 closed. As 32 moves vertically upwards, with the follower roller 40 moving over the surface 41, latching device 48 is closed and the profiled slide 46 locked in position. The said latching device 48, in fact, remains closed all the time the follower roller 40 is on surface 42 or 43 and 44. After the roller 40 moves on to surface 44, the latching device 47 is opened and the movement desired for the next overlap" downstroke of 32-is selected while roller 40 is on surface 44, by moving the profiled slide 45 to the desire position. As the roller 40 moves from surface 41 to surface 44, over surface 42 or 43, the guide bar 39 moves longitudinally.

0n the downstroke (producing'the overlap) the latching device 47 is closed, the guide bar d is shogged, latching device 43 is opened, and the next desired movement for underlap selected while roller 40 is on surface 41. The guides are swung through the line of needles while roller 40 is on surface 41 and again while this same roller is on surface 44.

The overlap stroke can be faster than the underlap stroke as the former is usually a movement over no more than two needle spaces. The relative speeds of the strokes are controlled from the shape of the cam 31.

In the timing diagram constituting FIG. 5A, the double arrowed curved lines p, q, r and u respectively represent:

Line p radius arm 36 ascending during knitting machine underlap.

Line q dwell period when guides d pass through the line of needles c.

Line r -radius arm descending during knitting machine overlap.

Line u-another swell period when guides pass through line of needles.

The hereinbefore described driving units are, as previously mentioned, designed to separate the selection of the requirement of a guide bar from the actual] longitudinal shogging thereof. The accuracy of actuation is built into the driving unit via the latching devices, rather than into the selection or program unit. The system thus permits the use of selection or program units which need not be as accurate as conventional cams or cam links. The system also allows the use of program units which are move versatile than those used heretofore, and one such unit is used for all fabric designs.

A typical separate electropneumatic program unit PU is illustrated in FIG. 6. Thus, as will be seen in this FlG., such a unit for one guide bar consists of two banks of pnuematic cylinders, each bank operating one profiled slide. The six cylinders 55-60 are arranged in series, each controlled by an electromagnetic solenoid 61-66 respectively, and operate the upper profiled slide. A similar series of cylinders 67-72 controlled by solenoids 73-78 operate the lower profiled slide. Cylinder 60 is shown in detail. The movements produced by individual cylinders are as follows:

Cylinders 55 and 67 One needle spacing 56 and 68 Two needle spacings 57 and 69 Four needle spacings 58 and 70 Eight needle spacings 59 and 71 Ten needle spacings 60 and 72 Sixteen needle spacings Cylinders 55 and 67 are fixed by their stems 79 and 80 respectively. Cylinders 56-60 slide on rail 31, each on bearings 82 as shown for cylinder 60. 83 is a guide rod. Similarly, cylinders 68-72 slide on rail 84, 85 being a guide rod.

The output member from cylinder 55 pushes the body of cylinder 56. The output from 56 pushes the body of cylinder 57, etc., while the output member 86 from cylinder 60 pushes the upper profiled slide. The lower bank of cylinders operates in the same way, the output rod 37 from cylinder 72 pushing the lower profiled slide. The return mechanism is obtained from springs in the driving unit. When any particular cylinders in one bark are actuated, the movements produced by each one are thus additively combined in the resultant movement of the output member, e.g., if cylinders 55, 57 and 58 are actuated, the profiled slide will be driven to a position 1141-8 =13 needle spacings from the zero position. In conjunction with the driving unit this system enables a guide bar to be located in any one of forty two adjacent positions, each separated by the distance of one needle spacing.

For a multibar machine, each guide bar has a selection or program unit and a driving unit, although in fact these composite units would be designed specifically for multibar operation.

A principal advantage of the invention is that it overcomes the major problem of making samples efficiently on multibar machines producing complicated patterns. Using a conventional system, a new pattern chain can take 6-12 weeks to produce and cost in the order of 5,000 dollars. If the sample turns out to be unsatisfactory, the chain links cannot usually be easily used in other designs. For use in conjunction with the invention, a program on peg board or on punched tape can be produced in 2-3 hours, the major cost being labor. The invention thus enables a very rapid change of design and small corrections, or alterations, to the design can be made while the machine is actively knitting providing the same threading setout is used.

lna production machine it may sometimes be an advantage to use for the selection mechanism a chain made up of standardized links of lower accuracy than those used conventionally. The cost of such a chain would be much lower than usual and the links would be reusable in any other design.

I claim:

1. In a warp knitting machine, in combination, a needle bar which is movable up and down; needles carried by said bar; guide bars each of which is adapted to be shogged longitudinally to different extents; sets of guides provided on said guide bars and having eyes through which can be passed individual warp threads; a beam from which said threads are drawn, said needle bar and the guide bars being cooperable in the production of warp knitted fabric; and a mechanism for controlling the longitudinal shogging movements of each of relevant guide bars; wherein the improvement resides in the form of the said controlling mechanism which is designed to separate selections of the said longitudinal movements from a driving influence actually effecting the latter and for this purpose comprises in respect of each such guide bar, in combination, (a) a driving unit incorporating both means providing a cam face and operable to vary the profile thereof and also continuously driveable means for following such face and conveying varying longitudinal movements to the guide bar by cam action; and (b) a separateprogram unit the outputs from which effect variations in the profile of the cam face, (a) functioning to move the guide bar longitudinally after (b) has determined the extent and direction of such movement.

2. A combination according to claim 1, wherein the driving unit (a) in respect of each guide bar concerned comprises relatively movable components individually profiled to provide portions of the variable cam face; a first member which is connected at one end with a link arranged to bear upon the guide bar and is arranged at the other end to follow the cam face; and a second member which is connected to the first member and is continuously driven by drive means so as to move the relevant end of the first member to and fro relatively to the cam face.

3. A combination according to claim 2, wherein the separate program unit (b) is constructed and operable to effect selective movements of the profiled components relatively to one another suchwise as to modify the cam face and subsequently change the position of the relevant guide bar by a longitudinal movement thereof the extent and direction of which have previously been determined by (b).

4. A combination according to claim 3, wherein latching devices are provided to accurately locate and lock the individually profiled components in the positions to which they are selectively moved by the separate program unit (b).

5. A combination according to claim 4, wherein each driving unit (a) includes a pair of individually profiled components in the form of slides, and one latching device per slide.

6. A combination according to claim 5, wherein each latching device of a driving unit (a) comprises opposed rows of pivoted teeth formed respectively on the relevant profiled slide and an adjacent latch element, the said element being movable towards and away from the profiled slide, to respectively lock and unlock the latter by engagement and disengagement of the teeth of one row in and from the V-shaped notches between the teeth of the opposed row in a direction transverse to longitudinal movements of the said slide the effecttve gauge, l.e., pitch, of the teeth being related to the gauge of the needles of the warp knitting machine.

7. A combination according to claim 6, wherein each latch element is movable in a direction perpendicular with respect to the line of longitudinal movement of the corresponding profiled slide, the said latch element being mounted in a block movable in a fixed part of the driving unit (a).

8. A combination accordingto claim 7, wherein the movable blocks are so spring biassed as normally to hold the latch elements apart from the profiled slides, and which includes means operable in time with the warp knitting machine to move the latch elements into engagement with the profiled slides against the spring action.

9. A combination according to claim 2, wherein the first member of each driving unit (a) consists of a radius lever which at one end is pivotally connected to a slidable crosshead in turn connected to a link arranged to bear upon the opposed end of the relevant guide bar, and at its opposite end is furnished with a follower arranged to run on and over the variable cam face.

10. A combination according to claim 9, wherein at least part of a profiled end of each of the relatively movable components in the form of slides provides a cam face portion in the shape of an arc whose radius is the effective length of the radius lever.

11. A combination according to claim 10, wherein the variable cam face of each driving unit (a) is made up of three segments, viz the arcuate ends of the two relatively pivotally slides and a bridging link which presents a planar surface and is pivotally connected at its ends to the slides, whereby relative longitudinal movements of said slides cause the planar surface to assume various inclinations to vary the profile of the cam face.

12. A combination according to claim 2, wherein the second member is slidable upwards and downwards in bearings, the timing of the movements of the member being controlled by the peripheral contour of a double-acting cam mounted on a drive shaft of the warp knitting machine, and there being pivotally mounted upon the said second member two opposed two-armed levers furnished with rollers constituting hearings for the first member.

13. A combination according to claim 12, wherein a follower on a radius arm constituting the first member is arranged to run over faces on the profiled ends of two relatively movable slides, one of two faces on each slide being in the form of an arc of radius equal to the effective length of the radius arm and the other face on the slide being planar.

14. A combination according to claim 5, wherein each program unit (b) is of an electropneumatic character, the movements of the profiled slides being effected through the medium of pneumatic cylinders and associated output shafts arranged for action upon the said slides.

15. A combination according to claim 14, wherein each program unit (b) comprises, for the relevant guide bar, two banks of pnuematic cylinders, the cylinders of each bank being arranged in series and each controlled by an electromagnetic solenoid, each bank operating one profiled slide, and the individual cylinders being adapted when energized to produce movements to the extents of the various needle spacings.

16. A combination according to claim 15, wherein the pneumatic cylinders of each bank are coaxially disposed and slidable along a common rail, the output member from each cylinder being arranged to push against the body of the next cylinder ahead with the exception of the last cylinder at the appropriate end of the series from which last cylinder extends an output shaft disposed to push the relevant profiled slide. 

1. In a warp knitting machine, in combination, a needle bar which is movable up and down; needles carried by said bar; guide bars each of which is adapted to be shogged longitudinally to different extents; sets of guides provided on said guide bars and having eyes through which can be passed individual warp threads; a beam from which said threads are drawn, said needle bar and the guide bars being cooperable in the production of warp knitted fabric; and a mechanism for controlling the longitudinal shogging movements of each of relevant guide bars; wherein the improvement resides in the form of the said controlling mechanism which is designed to separate selections of the said longitudinal movements from a driving influence actually effecting the latter and for this purpose comprises in respect of each such guide bar, in combination, (a) a driving unit incorporating both means providing a cam face and operable to vary the profile thereof and also continuously driveable means for following such face and conveying varying longitudinal movements to the guide bar by cam action; and (b) a separate program unit the outputs from which effect variations in the profile of the cam face, (a) functioning to move the guide bar longitudinally after (b) has determined the extent and direction of such movement.
 2. A combination according to claim 1, wherein the driving unit (a) in respect of each guide bar concerned comprises relatively movable components individually profiled to provide portions of the variable cam face; a first member which is connected at one end with a link arranged to bear upon the guide bar and is arranged at the other end to follow the cam face; and a second member which is connected to the first member and is continuously driven by drive means so as to move the relevant end of the first member to and fro relatively to the cam face.
 3. A combination according to claim 2, wherein the separate program unit (b) is constructed and operable to effect selective movements of the profiled components relatively to one another suchwise as to modify the cam face and subsequently change the position of the relevant guide bar by a longitudinal movement thereof the extent and direction of which have previously been determined by (b).
 4. A combination according to claim 3, wherein latching devices are provided to accurately locate and lock the individually profiled components in the positions to which they are selectively moved by the separate program unit (b).
 5. A combination according to claim 4, wherein each driving unit (a) includes a pair of individually profiled components in the form of slides, and one latching device per slide.
 6. A combination according to claim 5, wherein each latching device of a driving unit (a) comprises opposed rows of pivoted teeth formed respectively on the relevant profiled slide and an adjacent latch element, the said element being movable towards and away from the profiled slide, to respectively lock and unlock the latter by engagement and disengagement of the teeth of one row in and from the V-shaped notches between the teeth of the opposed row in a direction transverse to longitudinal movements of the said slide, the effective gauge, i.e., pitch, of the teeth being related to the gauge of the needles of the warp knitting machine.
 7. A combination according to claim 6, wherein each latch element is movable in a direction perpendicular with respect to the line of longitudinal movement of the corresponding profiled slide, the said latch element being mounted in a block movable in a fixed part of the driving unit (a).
 8. A combination according to claim 7, wherein the movable blocks are so spring biassed as normally to hold the latch elements apart from the profiled slides, and which includes means operable in time with the warp knitting machine to move the latch elements into engagement with the profiled slides against the spring action.
 9. A combination according to claim 2, wherein the first member of each driving unit (a) consists of a radius lever which at one end is pivotally connected to a slidable crosshead in turn connected to a link arranged to bear upon the opposed end of the relevant guide bar, and at its opposite enD is furnished with a follower arranged to run on and over the variable cam face.
 10. A combination according to claim 9, wherein at least part of a profiled end of each of the relatively movable components in the form of slides provides a cam face portion in the shape of an arc whose radius is the effective length of the radius lever.
 11. A combination according to claim 10, wherein the variable cam face of each driving unit (a) is made up of three segments, viz the arcuate ends of the two relatively pivotally slides and a bridging link which presents a planar surface and is pivotally connected at its ends to the slides, whereby relative longitudinal movements of said slides cause the planar surface to assume various inclinations to vary the profile of the cam face.
 12. A combination according to claim 2, wherein the second member is slidable upwards and downwards in bearings, the timing of the movements of the member being controlled by the peripheral contour of a double-acting cam mounted on a drive shaft of the warp knitting machine, and there being pivotally mounted upon the said second member two opposed two-armed levers furnished with rollers constituting hearings for the first member.
 13. A combination according to claim 12, wherein a follower on a radius arm constituting the first member is arranged to run over faces on the profiled ends of two relatively movable slides, one of two faces on each slide being in the form of an arc of radius equal to the effective length of the radius arm and the other face on the slide being planar.
 14. A combination according to claim 5, wherein each program unit (b) is of an electropneumatic character, the movements of the profiled slides being effected through the medium of pneumatic cylinders and associated output shafts arranged for action upon the said slides.
 15. A combination according to claim 14, wherein each program unit (b) comprises, for the relevant guide bar, two banks of pnuematic cylinders, the cylinders of each bank being arranged in series and each controlled by an electromagnetic solenoid, each bank operating one profiled slide, and the individual cylinders being adapted when energized to produce movements to the extents of the various needle spacings.
 16. A combination according to claim 15, wherein the pneumatic cylinders of each bank are coaxially disposed and slidable along a common rail, the output member from each cylinder being arranged to push against the body of the next cylinder ahead with the exception of the last cylinder at the appropriate end of the series from which last cylinder extends an output shaft disposed to push the relevant profiled slide. 